4. PROGRAMS, MISSIONS, AND PAYLOADS

STS-51B/Spacelab 3

MISSION PROFILE: STS-51B/Spacelab 3

Mission Duration: 7 days

Date: April 28-May 5, 1985

Life Sciences Research Objectives
Evaluate operations and procedures for in-flight care of animals
Assess in-flight
biocompatibility between animals and RAHF
Study physiological, morphological
and behavioral changes in animals

The STS-51B mission was launched onboard the Space Shuttle
Challenger on April 28, 1985 and recovered on May 5, 1985. The mission was also
called Spacelab 3 (SL-3), because it was the third Shuttle mission scheduled
to use the Spacelab.

Although the primary objective of the STS-51B
mission was to conduct materials science experiments in a stable low-gravity
environment, important research was conducted in life sciences, fluid mechanics,
atmospheric science, and astronomy. Scientists from the U.S., France, and India
carried out a total of 15 investigations in these disciplines. The Shuttle carried
a crew of seven, including two payload specialists and three mission specialists.

Several life sciences investigations using nonhuman
subjects were conducted on the mission. This research was particularly significant
because it involved the introduction and flight verification of the Research
Animal Holding Facility (RAHF). The RAHF is a self-contained system that houses
and provides life support for animals in space. Two RAHFs were flown on the
mission, one contained 24 rats and the other contained 2 squirrel monkeys.

Life Sciences Research Objectives

The primary life sciences research objective of the
mission was to evaluate the RAHF's capability to maintain animals in an environment
comparable to a ground-based vivarium. This is vital to experiments conducted
in space because uncompromised data on the physiological and behavioral effects
of microgravity can only be obtained from healthy animals. In addition to fulfilling
this objective, the mission provided valuable baseline data on various physiological
parameters. The mission was also able to address the issue of possible risks
to the crew's health and comfort. This was of some concern because for the first
time, crew members and animals were confined together within the enclosed environment
of the Spacelab.

Specifically, the research objectives for the
SL-3 mission were to: evaluate operations and procedures for in flight animal
care; assess in-flight biocompatibility between the animals and the RAHF; gain
mission operational experience; study the physiological, morphological and behavioral
changes that occur in animals as a result of being contained in the RAHFs during
space flight; and verify the principal hardware elements to be flown on later
missions.

Life Sciences Payload

Organisms

Two adult male squirrel monkeys(Saimiri
sciureus) were flown unrestrained in individual cages in the primate RAHF.
The objective in flying these animals was to observe gross physiological and
behavioral changes in response to space flight, and to evaluate the adequacy
of the RAHF to house and support them in space.

Both monkeys were
free of various specified pathogens. Only six months prior to flight, it was
decided that the monkeys should also be free of antibodies to the Herpes saimiri
virus, because of crew safety considerations. Although the Herpes saimiri virus
is not known to cause disease in either squirrel monkeys or humans that carry
it, problems have been documented in other species. A worldwide search was initiated
to find Herpes saimiri-free animals. Five were eventually located, but time
limitations permitted only two of them to be trained for flight. Instruments
were not implanted in the monkeys because of time constraints.

Rattus norvegicus, rat

The rodent RAHF
contained 24 individually housed male albino rats (Rattus norvegicus)
that were certified free of several specific pathogens.
Half of the rats were rapidly growing juveniles, weighing approximately 200
grams at flight. The remainder were mature 12-week old rats, weighing approximately
400 grams at flight. All rats were flown unrestrained. Before the flight, four
of the rats were surgically implanted with biotelemetry transmitters.

Each primate cage contained a removable solid
window through which crew members could view the animal (Fig. 4-26). A perforated
window beneath this allowed limited access to the animal. A temporary restraint
system could be activated to restrain the animal in flight in the event of an
emergency. Airflow directed urine and feces to absorbent, removable trays beneath
the grid floor of the cage. Two infrared light sources and two activity sensors
located at opposite sides of the cage were used to monitor animal movement.
Periodic video recordings were made of the monkeys to evaluate their response
to space flight.

Figure 4-26: Primate cage in the RAHF.

Rodent cages were similar in design to the primate
cages (Fig. 4-27). Two rats were housed in each cage, separated by a partition.
A camera mirror system was installed to record the movements and behavior of
four of the rats during launch and re-entry.

The RAHFs were designed to provide life support
in a manner comparable to vivarium housing on the ground. Besides providing
access to food and water and effective waste removal, the facility also permitted
environmental factors such as lighting, temperature, and humidity to be maintained
within a specified range. An environment control system circulated conditioned
air through the cages to control temperature and humidity, and facilitated air
exchange with the Spacelab.

Food and water consumption were monitored as
an indicator of animal well-being and a measure of the normalcy of circadian
periodicity. Water consumption was measured electronically when the Lixit reservoirs
in the cages refilled after being emptied by the animals. Animals could manipulate
a tap switch to activate feeders filled with banana pellets. A pellet counter
monitored food consumption. Rodent food was presented in the form of a bar.
The food bar advanced as the rodents gnawed on its end, and consumption was
monitored by an event counter which sensed the forward movement of the bar.

The crew evaluated general animal well-being
through the viewing windows on the cages, and by monitoring food and water intake
using the Spacelab computer. An onboard control panel could alert crew members
to hardware malfunctions such as water leaks.

Figure 4-27: Rodent cage in the RAHF.

An automated biotelemetry system (BTS) was used
to monitor animal body temperature, heart rate, and electrocardiograms. The
BTS consisted of a surgically implanted transmitter, an antenna on each RAHF
cage, a receiver, and electronic interfaces with a dedicated computer. The output
from the implanted sensors first went to an onboard computer, which reformatted
the data and then transmitted it to the ground.

There were four monkey cages in the primate RAHF
equipped with BTS capability. However, physiological data was not obtained from
the two flight monkeys because neither was outfitted with sensors. Physiological
data was obtained from the four rats implanted with biotelemetry transmitters.

Operations

The execution of the mission involved simultaneous activities at three NASA
centers: Hangar L at KSC in Florida, ARC in California, and the Payload Operations
Control Center at JSC in Texas. Although the mission was successful, several
obstacles had to be overcome at various stages during mission development and
the in-flight period.

Design, testing, and successful hardware integration
required a major cooperative effort between the various NASA centers involved
in the mission. The RAHF was originally designed as an animal transporter to
be launched in the middeck of the Shuttle. It was to be installed in the Spacelab
after launch. This concept was abandoned because it was difficult to move the
bulky transporter down the tunnel connecting the middeck and Spacelab. The idea
of mounting the transporter in the Spacelab aisle in order to maintain the vertical
orientation of the animal cages at landing also turned out to be impracticable.
The final design involved installing individual cages in the RAHF while the
Shuttle was in its vertical position on the launch pad. This meant that the
animals would be resting on the cage side at landing.

A winch system, the Module Vertical Access Kit
(MVAK), was designed to perform the complicated operation of loading animal
cages and personnel from the middeck of the vertically oriented orbiter into
the Spacelab below, while on the launch pad (Fig. 4-28).

Figure 4-28: The MVAK allows biological materials to
be loaded into the Spacelab late in the STS launch sequence, after the spacecraft
has been assembled and placed in vertical position: (a) orbiter middeck;
(b) animal cage being lowered through tunnel connecting middeck and Spacelab;
(c) Spacelab; and (d) RAHF.

Mission operation procedures alsohad to be modified
considerably to accommodate animal welfare and life sciences experiment requirements.
Late loading of animals into the Spacelab before launch was vital because of
animal welfare concerns and because this operation had to be performed during
the light phase of the animals' light/dark cycle. Likewise, early removal after
landing was necessary in order to conduct postflight studies on the animals
before they readapted to Earth gravity.

The main problem that arose during flight was
the release of particulates from the animal enclosures into the Spacelab during
maintenance operations. Despite the considerable publicity drawn to this problem,
postflight analyses showed that neither the crew nor the animals were adversely
affected. However, it was recommended that the faulty subsystems be redesigned
before flying the hardware a second time. Malfunctions in the leak alarms for
the water systems in the primate cages and in three of the rodent cages were
also noted. The monkeys' drinking behavior pattern in space set off the leak
alarms, pointing to a need for higher leak alarm settings in future missions.
Fouling of activity sensors, viewing windows, and temporary restraint systems
occurred because of the way in which the animals oriented themselves during
waste elimination. No other significant problems were observed in flight, and
the hardware was shown to be capable of being flown again after modification.

The orbiter's landing site was changed from KSC
to the Dryden Flight Research Facility in Southern California approximately
two weeks before the mission. Postflight procedures had to be hastily revised
to accommodate this change, but the animals were recovered without incident.

Results

The monkeys and rats were recovered in good condition, healthy and free of
microbiological contaminants. Postflight tissue analyses were not performed
on the flight monkeys. The flight rats were euthanized a few hours after recovery
and their tissues subjected to a variety of tests. Control rats on the ground
were euthanized and analyzed in the same manner shortly after. Several changes
were noted in the flight animals as compared with ground control animals. These
changes are summarized below. Detailed results of science studies are categorized
by discipline and described in Appendix 1.

Squirrel Monkeys

Both monkeys ate less food and were less active
in flight than on the ground. One monkey adapted quickly to the microgravity
condition. The other monkey exhibited symptoms characteristic of Space Adaptation
Syndrome, consuming no food and little water during the first four days of flight.
On the fifth day of flight, after being hand-fed banana pellets by the crew,
its behavior became more comparable to that of the first flight monkey.

Rodents

Some of the changes seen in flight rats, such
as absence of interferon production by spleen cells, lower plasma concentration
of osteocalcin, and heightened marrow sensitivity to erythropoietin, may have
been influenced by the 12-hour period between landing and sample acquisition.

Postflight analyses of rat tissue indicated that
the rats had not been exposed to prolonged or significant stress. Growth curves
were parallel for all rats. The rats consumed more water during the mission,
the circadian rhythm of food intake changed, and body temperature decreased
during the animals' active phase.

The rats had decreased muscle tone and muscle
mass after flight. There was a shift from aerobic to glycolytic metabolism.
More fast- twitch muscles were seen in the rats' soleus muscles after flight.
Significant changes were also noted in the bone of the flight rats. Bone mass,
and bending and tensile strength were reduced. Bone changes that occurred during
this 7-day mission were found to be much greater than the changes noted in tail
suspension studies (simulated microgravity studies) conducted for 28 days. Spleen
cell production of interferon significantly decreased, which may be indicative
of an impaired immune response.

Metabolic changes noted included a shift from
a lipid-based to carbohydrate-based metabolism. Changes were seen in brain metabolism
and receptors and in the vestibular apparatus. Growth hormone synthesis was
decreased. Thymus gland and testes weights were reduced after flight. In cardiac
muscle, glycogen and lipid deposition increased and muscle cell microtubules
decreased.

In general, the postflight changes noted in rats
were similar to the changes observed in humans, and were consistent with the
findings of the Soviet Cosmos program.

The life science research objectives of the SL-3
mission were accomplished in no small measure. Operations and procedures developed
for mission care of the animals were satisfactory. These included the design
modifications made to the RAHFs and the STS to accommodate the payload, the
MVAK procedures, late and early access procedures to ensure animal welfare and
uncompromised science results, and crew operations within Spacelab. Recovery
of healthy unstressed animals demonstrated that the RAHFs were capable of adequately
housing and supporting animals in space. The operational experience gained by
the personnel involved was expected to be valuable for conducting more complex
missions in the future. The amount of data gathered on the physiological, behavioral,
and morphological responses of the animals to microgravity surpassed all expectations.
The hardware being flight tested was verified from an operational and engineering
standpoint and subsystems requiring modifications were identified.

Fast, T., et al. Rat Maintenance in the Research Animal Holding Facility
during the Flight of Spacelab-3. Abstract S-187-188, Proceedings of the
7th Annual Meeting of the IUPS Commission on Gravitational Physiology, Niagara
Falls, New York, October 1985.